Iris scanning

The user places himself so that he can see his own eye's reflection in the device. The user may be able to do this from up to 50 cm away or may need to be as close as a 5 cm depending on the device. Verification time is generally less than 5 seconds, though the user will only need to look into the device for a few seconds. To prevent a fake eye from being used to fool the system, these devices may vary the light shone into the eye and watch for pupil dilation.

The uniqueness of eyes, even between the left and right eye of the same person, makes iris scanning very powerful for identification purposes. The likelihood of a false positive is extremely low and its relative speed and ease of use make it a great potential biometric. The only drawbacks are the difficulty in getting someone to hold their head in the right spot for the scan if they are not doing the scan willingly. It also takes up a fair amount of memory for the data to be stored, but with the advances in technology, this is unlikely to cause any major difficulty.

Iris scans analyse the features that exist in the colored tissue surrounding the pupil which has more than 200 points that can be used for comparison, including rings, furrows and freckles. The scans use a regular video camera style and can be done from further away than a retinal scan. It will work through glasses fine and in fact has the ability to create an accurate enough measurement that it can be used for identification purposes, and not just verification.